At Saturday's concert Dave Grohl said that he wanted to make the most of their performance as he was unsure when they would be performing together again. In his letter on Facebook he said “Yes... I was serious. I'm not sure when the Foo Fighters are going to play again”. But, do not despair! He followed this up by saying “I never want to NOT be in this band. So, sometimes it's good to just... put it back in the garage for a while...” He also referred to the band as his 'family', his 'life' and his 'world'.
Grohl also encouraged fans that they would all see more of his work very soon, as the hiatus allows him to work on his latest project, a documentary called 'Sound City' which he referred to as the “most important project [he's] ever worked on.”
While it certainly is a shame that there wont be any new music to come from Foo Fighters for a while, with an 18 year history there's still plenty of their music to indulge in. And if it's specifically Dave Grohl that you love, then the many, many other bands and projects he has been involved with (Nirvana, Them Crooked Vultures, Queens Of The Stone Age, etc.) will keep you entertained for months, if not years.